Application of Coriolis Mass Flowmeter in Food Processing

Introduction and principle of mass flow meter

The volume of fluid is a function of fluid temperature and pressure, and is a dependent variable, while fluid quality is a quantity that does not change with time, space temperature, and pressure. As mentioned earlier, among the commonly used flow meters, such as orifice flow meters, laminar mass flow meters, turbine flow meters, vortex flow meters, electromagnetic flow meters, rotameters, ultrasonic flow meters, and oval gear flow meters, etc. The flow measurement is the volume flow of the fluid. The amount of fluid involved in activities such as scientific research, production process control, quality management, economic accounting, and custody transfer is generally of quality. Using the above-mentioned flowmeter to measure only the volume flow rate of the fluid often cannot meet people's requirements, and it is usually necessary to try to obtain the mass flow rate of the fluid. In the past, the quality of the fluid could only be obtained indirectly through methods such as correction, conversion, and compensation after measuring the temperature, pressure, density, and volume of the fluid. With this measurement method, there are many intermediate links, and the accuracy of mass flow measurement is difficult to guarantee and improve. With the development of modern science and technology, some metering methods and devices for directly measuring mass flow have appeared one after another, which has promoted the progress of flow measurement technology.

Coriolis mass flowmeter (hereinafter referred to as Coriolis mass flowmeter) is a direct mass flow measurement instrument with broad application prospects. At the same time, it can perform multi-parameter measurement of physical quantities such as density and frequency. However, with the development of industry, more and more occasions require Coriolis mass flow meters to be able to measure the flow of gas-containing liquids. The flow of gas-containing liquid is caused by the needs of production or process on the one hand: In production, the gas needs to be evenly mixed in the liquid to be tested, such as shampoo, ice cream, etc. On the other hand, the actual working conditions are unavoidable: In occasions such as oil loading, food batch processing and liquid filling, it is necessary to measure the short-term batch flow rate. At this time, the pipeline will experience "empty-full-empty" The gas-liquid two-phase process. For example, in food processing, in order to achieve sanitation permits, after the end of each batch of materials and before the start of the next batch of materials, the residues on the pipeline need to be completely cleaned up, so that the next batch of materials will experience "empty-" Full" process. However, gas-containing liquid flow measurement is a difficult problem for Coriolis mass flowmeters. It puts forward higher requirements on the driving technology and signal processing technology of Coriolis mass flowmeters. At the same time, due to the large error in the original measurement of the flow, error correction technology is needed for later correction to improve the accuracy of the measurement.

Increasing the update speed and stability of the drive signal can better maintain the vibration of the flow tube, improve the quality of the sensor signal, and provide a better basis for gas-containing liquid flow measurement; the use of appropriate signal processing methods can reduce the flow rate of gas-containing liquid The original measurement error; the measurement error under the gas liquid flow can be corrected by using appropriate error correction technology. Therefore, Coriolis mass flowmeter measurement of gas-containing liquid flow mainly includes three key technologies, namely drive technology, signal processing technology and error correction technology. Many scholars have conducted research from these three aspects and have made good progress.

However, the measurement accuracy of Coriolis mass flowmeter under gaseous liquid flow cannot meet the measurement requirements of 0.1-level accuracy in industrial practical applications, and there are few research reports on Coriolis mass flowmeter measuring gaseous liquid flow. To this end, this article reviews the three aspects of driving, signal processing, and error correction. It analyzes the difficulties of driving, signal processing and error correction technology under gas-containing liquid flow, and summarizes the best under gas-containing liquid flow. Drive technology, signal processing technology and error correction technology. Explore the reasons for the large error in the original measurement of gas-containing liquid flow and the reason why the measurement accuracy after correction using the correction method still cannot reach the single-phase flow measurement accuracy of 0.1, and provide ideas for improving the accuracy of the Coriolis mass flowmeter to measure the gas-containing liquid flow. .#Coriolis Mass Flow Meter#